Comparative study of the elasticity and memory of intraocular lens loops

The elasticity and memory of intraocular lens loops was tested by manufacturing lenses with matching physical properties but with loops of either polypropylene or VS-100 polymethylmethacrylate (PMMA). After establishing the reliability of measurements, these lenses were compressed under physiologic conditions for up to three years. The rates and extent of reexpansion of the loops were then measured. Given loops of equivalent initial flexibility, VS-100 PMMA has less long-term tendency to reexpand to its initial shape than polypropylene.